PREFACE. IX 



Tims we sometimes find one species described as 

 having "the fore limbs short," and the next, which 

 is to be distinguished from it, not as having " the 

 fore limbs long," but " the anterior extremities 

 elongated." Sometimes in the long descriptions 

 which must be waded through, and carried in mind, 

 the head in one case is mentioned first, then the 

 tail, then the trunk, the limbs, and so on : but in 

 the succeeding example, which has to be compared 

 with it, perhaps the limbs come first, then the head, 

 then the trunk, &c. Such difficulties as these are 

 most perplexing ; and yet it is easy to see that a 

 little care might entirely remove them. If a cer- 

 tain order were maintained in the details of de- 

 scription of kindred forms, and a fixed phraseology, 

 I need not point out how much the work of com- 

 parison would be lightened. 



In the wording of the following definitions I 

 have endeavoured to make the phraseology as 

 Saxon as possible. I am far from desiring to rob 

 our language of its Latin element; it would be 

 greatly impoverished by such a privation; and 

 multitudes of words of Latin derivation are as 

 familiar as the homeliest Anglo-Saxon. Still our 

 scientific language might be much more Saxonised 

 than it is, without losing that precision which is 

 indispensable. 



On the other hand, the student must bear in 

 mind that so many of the ideas themselves in 



